'This package is blocked because it wants to overwite files belonging to other packages (see messages above). If you have no clue what this is all about report it as a bug for this package on https://bugs.gentoo.org.'

the packages you are trying to emerge want to overwrite mac os x system files.
if you are absolutely sure that this wont break your system you can disable this feature like so:
FEATURES="-collision-protect" emerge packagename

but that is a really bad idea and you will probably break your system if you do that._________________Could it be?